\documentclass[a4paper, 12pt]{book}
\usepackage[top=2cm, bottom=2cm, left=3cm, right=3cm]{geometry}
\usepackage[frenchb]{babel}	
\usepackage[T1]{fontenc}	
\usepackage[utf8]{inputenc}
\usepackage{calc}
\usepackage{ifthen}
\usepackage{fancyhdr}
\usepackage{xstring}
\usepackage{multicol}
\usepackage{parcolumns}
\usepackage{textcase}
\setlength{\headheight}{15pt}
\setlength\columnseprule{0.4pt}
\addtolength\columnsep{2pt}
\makeatletter

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%% Rubriques et vers %%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\makeatletter
address@hidden@incompletfalse
address@hidden
address@hidden
address@hidden
address@hidden
address@hidden address@hidden
address@hidden address@hidden

address@hidden@offset{.5ex}

\newenvironment{accogauche}[1][]{%
		\parskip = 0pt plus 0.3pt
	address@hidden@
	address@hidden@accotrue
	address@hidden
	address@hidden
}
{%
	\strut
	\egroup
	address@hidden@address@hidden
	address@hidden(address@hidden@box)/address@hidden@address@hidden
	address@hidden@text$\left\{\vrule width\z@ address@hidden address@hidden
	address@hidden@address@hidden@
	address@hidden
	address@hidden/address@hidden@address@hidden/address@hidden@box
	address@hidden@box
}

\newenvironment{accodroite}[1][]{%
		\parskip = 0pt plus 0.3pt
	address@hidden@
	address@hidden@accotrue
	address@hidden
	address@hidden
	address@hidden
}
{%
	\strut
	\egroup
	address@hidden@address@hidden
	address@hidden(address@hidden@box)/address@hidden@address@hidden
	address@hidden width\z@ address@hidden address@hidden@text}%
	address@hidden@box/address@hidden@address@hidden/address@hidden
	address@hidden@address@hidden@
	address@hidden
	address@hidden@address@hidden
}

\newcommand\ensemble[1]{%
    \vspace{2ex}%
    \begingroup
    		\parskip = 0pt plus 0.3pt
        \centering
        \textsc{#1}%
        \par\nobreak
    \endgroup
}

\newcommand*\pers[2][]{%
	\parskip = 0pt plus 0.3pt
	address@hidden@address@hidden@vspace{2ex}\else\vspace{2ex}\fi\else\vspace{2ex}\fi
	\noindent
	address@hidden@address@hidden
	address@hidden@address@hidden, \emph{#1}\fi}%
	\ifdim\dimexpr(address@hidden)/2\relax<address@hidden@length\dimexpr(address@hidden)/address@hidden
	\ifdim\dimexpr(address@hidden)/address@hidden@box>address@hidden@length\dimexpr(address@hidden)/address@hidden@box\fi
	\kern\dimexpr(address@hidden)/2\relax
	address@hidden@address@hidden
	address@hidden@box\par\nobreak
%	\parskip = 5pt plus 0.3pt%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
}

address@hidden
		\parskip = 0pt plus 0pt
    \par\noindent\hspace{#1}%
    address@hidden@address@hidden
    address@hidden
    \ifdim#1<address@hidden@length#1\fi
    address@hidden>address@hidden@address@hidden
    address@hidden@address@hidden }\fi
    address@hidden@address@hidden
    address@hidden@address@hidden@incomplet{#2 \normalsize}%
    address@hidden@empty
    \fi
    address@hidden
		\parskip = 5pt plus 0.3pt
}

address@hidden
	address@hidden
		address@hidden@vers{#2}}%
		address@hidden@vers{#2}}}%
}

\newcommand*\definitacteur[2][]{%
	\expandafter\newcommand\expandafter*\csname#2\endcsname[1][]{%
		address@hidden@empty\pers[##1]{#2}%
		\else\pers[##1]{#1}%
		\fi}%
}

address@hidden    {\dimexpr(0.5\linewidth-1 em)}
address@hidden  {\dimexpr(0.5\linewidth-2 em)}
address@hidden {\dimexpr(0.5\linewidth-3 em)}
address@hidden(0.5\linewidth-4 em)}
address@hidden  {\dimexpr(0.5\linewidth-5 em)}
address@hidden   {\dimexpr(0.5\linewidth-6 em)}
address@hidden  {\dimexpr(0.5\linewidth-7 em)}
address@hidden  {\dimexpr(0.5\linewidth-8 em)}
address@hidden  {\dimexpr(0.5\linewidth-9 em)}
address@hidden   {\dimexpr(0.5\linewidth-10em)}
address@hidden  {\dimexpr(0.5\linewidth-11em)}
address@hidden  {\dimexpr(0.5\linewidth-12em)}
address@hidden {\dimexpr(0.5\linewidth-12em)}
address@hidden(0.5\linewidth-12em)}

address@hidden@empty

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%% Parties et sections %%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\newcommand\titropera[1]{%
	\begingroup
		\centering
		\large\MakeTextUppercase{#1}%
		\par\nobreak
	\endgroup
}

\newcommand\partopera[1]{%
	\medskip
	\begingroup
		\centering
		\MakeTextUppercase{#1}%
		\par\nobreak
	\endgroup
}
\newcommand\parodair[2][]{%
	\begingroup
		\centering
		\emph{Sur #2}
		\ifx\empty#1\else\og{}#1\fg{}\fi%
		\par\nobreak
	\endgroup
}
\newcommand\couplet[1]{%
	\smallskip
	\begingroup
		\centering
		\lowercase{\textsc{#1}}
		\par\nobreak
	\endgroup
}
\newcommand\auteurcouplet[1]{%
	\nobreak\hfill#1\par
}